Loading patch for static tests



Sept. 19, 1944. WEAVER AL 2,358,369

LOADING PATCH'FOR STATIC TESTS Filed Dec. 31, 1943 FIG. 1v

/- vex/rags 506 4? 1?. 144:4:451? P404 f1. fflEM/VEQ yi i Y wings and other parts Patented Sept. 19, 1944 Edgar R. Weaver, Dayton e l Fairfield,0hio* 1 Application December 31, 194%; seen 3 Claims.

(Granted under the act of March amended April 30, 1928; 370 0.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to loading patches, which are flexible pads adapted to be cemented to the surfaces of an airplane to permit known loads to be imposed upon the latter while stationary, in so-called static tests. In our pending application Ser. No. 294,344 filed September 11, 1939,

,and r urn niner;

3, 1883, as G. 757) is preferably recessed as at l8 to receive rods l3, and the upright plate 1 may oscillate slightly relative to top plate 11, the blocks l4 and bolts l5 loading patches, each composed of sponge rubber,

adhering to two layers of rubber, are cemented to the top surfaces of an airplan to permit suspension of the entire airplane from cables attached to several of these patches, so a to subject the to tension, compression and shear stresses to test the strength and deflection of various parts of the airplane under controlled loads. However, rubber is a strategic material and is becomin increasingly scarce, and there is a 'need for a loading patch which con= tains no rubber whatever.

This invention aims to provide an improved loading patch containing no rubber which has adequate strength and which may be made to adhere firmly to any of the surfaces of an airplane or other structure under static tests.

In the accompanying drawing showing two embodiments of the invention:

Figure 1 is a perspective view, with parts broken away, of one form of loading patch, shown cemented to an airplane surface; and

Figure 2 is an end elevation of another form of the invention. v

Referring particularly to the drawing, the airplane part 4, only a fragment of which is shown, is suspended from a cable 5 by our novel loading patch, indicated generally at 6. An upright, fiat, elongated plate 1 is secured by a stud 8 and clevis 9 to the cable anchor l0, and serves as a hanger, bein located between and secured to two parallel angle bar ll, l2, in turn secured to the top of the loading patch body. Rods l3 (onlyone being shown) are welded to the lower edge of the fiat plate 1, and engage the bottoms of blocks I 4 arranged in pairs, each pair of blocks being secured by a bolt l5 and nut IE to the plate. Angle bars I l l2 are welded to the upper surface of a metal plate I! w -ch forms the top of the loading patch. In some instances plate I! may be of plywood. Top plate l1 may be appropriately curved (not shown) where the loading patch is to be secured to concave or convex surfaces, to obviate uneven distribution of tention in the body of the loading patch. Plate I! permitting such movement. Also the entire loading patch, and any part suspended from it, may oscillate on stud 8, whose axis is at right angles to theaxis of rods l3. The'described'arrangement permits the loading patch to accommodate itself to the load even though it i at an acute angle to the line of suspension throughcable 5. Many different constructions may b employed to suspend the loading patches ofour invention from a cable or other load-sustaining means, and the invention is not limited to use with any particular suspending means. 7

The body of the preferred loading patch is made entirely of cotton fabric, such as sized cotton duck, and comprises a top layer 20 of double filled duck, a bottom layer 2| of the sam material, and a cotton fabric looped member 22 providing a series of webs whichareunder tension when a load is applied. The loops aredouble stitched to the top layer 20 and to the bottom layer. 2|, as indicated at 23 and 24 respectively, and should be of material sufficiently strong to withstand a total load in tension of 2000 lb. or more. For some tests the patch will be about 24" x 6", having thickness (height) of about 1%! to 2". The top layer will becemented as at 25 to the underside of plate IT by a cement such as Goodrich 316M or Minnesota Mining E0613 j(a neoprene cement),'or any other glue having adequate strength and resistance to softening under'the conditions of the test, and the bottom layer 2| will likewise be cemented as at 26 to the airplane'surface 4. In the drawing, the thickness of the cement layers is of course exaggerated.

Now referring to Fig. 2, showing a modification (like parts being similarly numbered and hence not described a second time), in lieu of an all cotton body, we may employ a piece of sheepskin, with the skin layer '30 cemented as at 3| to the underside of the top plate I 1, and the wool fiber 32 cemented directly to the airplane structure 4, as indicated at33. No lower layer corresponding to layer 2| is required. Unbleached sheepskin would be preferred, since bleaching weakens the wool fibers. Such a patch will easily sustain a load of 2000 lb. in tension. In place of sheepskin, the skins of' goats, alpacas, llamas, dogs and other hairy or fur-bearing animals could be employed,

After completion of the tests, both form of loading patch are removed from surface 4 by employing a chemical which softens the cement without injuring the surface. Obviously the invention may be used in static tests of many objects other than airplanes.

What we claim is:

l. A loading patch entirely free of rubber and comprising an upper layer of flexible material adapted to, be se0ured-; to suspensiongmeans, and a plurality of spaced flexibl load-sustaining members of fibrous material secured to the upper)!!- layer and extending vertically downwardly there.-,v

flexible load-sustaining members ar a, plurality of loops formed from a single sheet of cotton duck or the like and stitched at their upperends to the upper layer, and a lower layer, also of cotton duck, is also stitched to the lower ends of the loops, the loops thus providing tension or load-carrying members. c

p 3. The. invention according to claim 1, wherein the flexible load-sustaining members are animal hair or WOOly fibers naturally secured to the skin from which they grew, the skin itself formirom and adapted to be temporarily secured; to a portion of the object to be tested.-;;:

2. The invention according to claim 1, wherein the upper layer is or cotton duct; or. the. like, the 1 ing saidupper layer.

EDGlAR R. WEAVER. PAUL H. KEMMER. 

